The present invention relates generally to curable coating compositions for the preparation of a protective release backing, i.e. a liner, for silicone pressure sensitive adhesives, herein also called SPSAs. In one aspect this invention relates to a unique organohydrogenpolysiloxane compound and to improved curable coating compositions comprising said compound. In a second aspect this invention relates to a unique fluorosilicone polymer and to improved curable coating compositions comprising said fluorosilicone polymer.
Recently, Brown and Stickles, U.S. Pat. No. 4,736,048, disclosed a fluorosilicone polymer, a curable composition, a release liner and a SPSA/liner laminate. Patentees' liner is said to be useful for releasing solvent-cast, heat-cured SPSAs with a force of no more than 200 grams per inch (g/in). However, the fluorosilicone coating compositions that are used by Brown and Stickles do not cure within 15 seconds at 121.degree. C.
Izumiya et al., Japanese Laid Open (Kokai) No. 225,581/87 disclose a release agent composition comprising a vinyl-substituted fluorosilicone polymer containing in-the-chain vinyl groups, a hydrogen-terminated fluorosilicone polymer containing in-the-chain silicon-bonded hydrogen atoms and chloroplatinic acid. Although this composition is said to provide a release liner having a peel adhesion of 110 g/25mm and a subsequent adhesion of 65% Patentees have not disclosed the cure rate and bath life for the composition and they have not taught the proportions of the fluorosilicone polymer and crosslinker to use. Regardless of the cure rate the disclosed composition would have little commercial value since its bath life would be unacceptably short in the absence of a catalyst inhibitor.